Lizards (phylum Chordata, subphylum Vertebrata, superclass Tetrapoda, class Reptilia, order Squamata, suborder Lacertilia) are reptiles with a slender body covered by scales, four limbs (hence the superclass Tetrepoda which means "four legs") and a tail. Some species, however, may have very reduced limbs or no limbs at all. The legless species may resemble snakes, but unlike the latter, most lizards have eyelids and external ears.
Lizards and snakes are of the same order, Squamata. They can be distinguished from other reptiles by their relatively slender bodies that are covered by scales; extremely movable upper jaws which allows them to swallow relatively large prey; and the males possessing penises that that in pairs (each called a hemipenis).
Like most other reptiles, they have limited physiological means to maintain the body temperature within a narrow range, and are more reliant on external heat sources. Like other vertebrates, they have a backbone with a spinal cord (a hollow tube of nervous tissue).
Depending on the species, lizards may lay eggs (oviparous), bear live young (viviparous), or bear live young from eggs brood within the body (ovoviviparous).
Many people dislike or even fear lizards, but most lizards are quite harmless and even help to control the population of insect pests in homes and gardens. Most lizards are also not venomous.
I have only seen some of the lizards that can be found in Singapore, and have photographed even fewer of them. I certainly hope to eventually see more species during my future trips so that I can update this blog post. Here are just some of those that I managed to photograph:
Family Varanidae
Varanid lizards, commonly called monitor lizards, are usually large lizards with sharp claws, a relatively long neck, a powerful tail, and a forked tongue, much like those of snakes. The tongue is extended every now and then to "taste" the air for the scent of food. Monitor lizards are mostly carnivorous, though a few species are known to be frugivorous (i.e. eat fruits). Studies have shown that some species of monitor lizards are venomous, and are closely related to snakes. They lay eggs with soft shells.
The Malayan Water Monitor (Varanus salvator) is one of the largest lizards in the world, being able to grow to about 3m long, though most are below 2m. It has thick and leathery skin with non-overlapping scales. Like other monitor lizards, it has a forked tongue.
The nostrils are positioned close to the tip of the snout. Young Malayan Water Monitors are black with yellow spots, while the adults are usually plain greyish brown. They can swim and climb very well, and are commonly seen in coastal areas such as mangroves, islands, and coral reefs. They are also often seen in agricultural areas, parks, canals, and reservoirs. During the breeding seasons, males can be seen fighting by standing on the hind legs and hugging each other, supported by the powerful tail, clawing at each other's back. Malayan Water Monitors feed on carrion or hunt for fishes and other small animals. They are often trapped by locals for their meat, which is consumed, and their hides, which can be made into leather products.
The Clouded Monitor (Varanus nebulosus) is smaller than the previous species, growing to about 1.7m long. Like other monitor lizards, it has and forked tongue, thick and leathery skin, and non-overlapping scales. Unlike the previous species, the snout is relatively short with the nostrils positioned midway between the eye and the tip of the snout. The skin is greyish brown in colour, densely marked with yellow spots. Clouded Monitors hunt for small animals by digging among the leaf litter with their sharp claws. They are usually found in the forests and scrubland.
Family Agamidae
Agamids generally have long legs and tails, but short heads. They have rough scales covering their bodies, and many species have a crest running down the head to the back of the body. They are usually diurnal and live in trees and bushes, descending to the ground only to move to another tree or to lay eggs. In many cases, the females bury their eggs in the soil. Most species feed on small animals, but some larger species feed on flowers, seeds and other plant parts as well.
The Changeable Lizard (Calotes versicolor) is an introduced species that is commonly seen in urban parks, scrubland and forest edges. It can change its colour, but not as dramatically or quickly as the chameleon. It is native to Peninsular Malaysia, Thailand and other parts of mainland Southeast Asia. Growing to about 38cm, this lizard has strongly keeled scales, a relatively large head, long slender limbs, a long tail and a spiny crest running down the back of its head to the back of the body.
This species is rather variable and changeable in colour, and can be yellow, green or brown (sometimes with darker patterns). Juveniles and females may have a pair of pale stripes along their backs.
It can be differentiated from similar species by the two spines above the ear opening. Male Changeable Lizards are bigger with swollen cheeks, and the heads turn orange during the breeding season. They can be seen nodding their heads and doing push-ups during this period to court the females and to deter rival males. Like other agamids, Changeable Lizards are oviparous.
The Green Crested Lizard (Bronchocela cristatella) is native to Singapore. While it is largely displaced by the previous species in urban areas and forest edges, it is still fairly common in parks that have many shrubs and trees, and in the forest. Growing to about 58cm long, it has a moderately slender body with small strongly keeled scales, long slender limbs, a very long tail, and a spiny crest at the back of its head.
Green Crested Lizards are usually bluish green in colour, but may change to dark brown, such as the male in the above picture, which changed from green to brown during courtship, but changed back to bright green after mating. They are diurnal, and are usually found on trees or bushes. The females bury their eggs in the soil.
The Common Flying Dragon (Draco sumatranus) is a gliding lizard which can glide from tree to tree. Growing to about 22cm long, it has a slender body with small scales, long slender limbs and a very long tail. The body is light brown, marked with darker and lighter blotches. There is a broad flap of skin (patagium) supported by ribs on both sides of its body which is black in colour with irregular brownish and greenish patterns. It glides by launching off into the air and extending its patagium, much like a gliding kite. The male has a bluish head and a large yellow throat flap, as featured in the picture above. The throat flap is usually extended for courtship purposes or to deter other males.
The female Common Flying Dragon lacks the bluish head, and has a much smaller throat flap. This oviparous species can be found in the forest, agricultural areas and parks.
The Black-bearded Flying Dragon (Draco melanopogon) grows to about 24cm long. Like the previous species, it has a slender body with small scales, long slender limbs and a very long tail. The back of the body is olive or green with greyish brown bars or blotches, while the patagium is black with many yellow spots. The throat flap of the males is black and orange, and hence the common name Black-bearded Flying Dragon. Like other gliding lizards, it can glide from tree to tree by extending the patagium at the sides of the body, and display the throat flap during territorial dispute or courtship. This oviparous species is usually found in mature forests.
The Five-banded Flying Dragon (Draco quinquefasciatus) grows to about 27cm, and is usually found in mature forests, often near water bodies. While it is also greenish in colour, it can be differentiated from the previous species by the five dark bands marked with numerous white spots across its back, and the pinkish-orange patagium. The throat flap of the male is yellow in colour, while those of the female is greenish with yellowish spots.
Family Gekkonidae
Gekkonid lizards, commonly called geckos, have thin and delicate skin with tiny scales and large eyes without movable eyelids. Most species are nocturnal, but some are diurnal or both. If they are caught by the tail, they are able to break it to escape while the broken tail continues to wriggle about to confuse the predator. A new tail will eventually grow to replace the lost one. Some geckos have expanded fingers and toes functioning like adhesive pads. The underside of these pads is lined a series of skin flaps with numerous microscopic hook-like hairs which allow the gecko to walk on vertical surfaces and even upside-down. Geckos are oviparous.
The Spiny-tailed House Gecko (Hemidactylus frenatus) is a very common gecko in human habitations, and sometimes in the forest. It can grow to about 13cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes and fingers are expanded into adhesive pads. The colour of this lizard is rather variable, but is generally a pale greenish brown with irregular darker speckles. The tail has numerous spiky structures (tubercles). This oviparous gecko can be active both in the night and in the day, hunting for insects.
The Mourning Gecko (Lepidodactylus lugubris), also known as the Maritime Gecko, is quite widespread in Singapore though more commonly seen in coastal habitats. It can be seen in scrublands, coastal forests, mangrove forests, and sometimes in buildings. It can grow to about 10cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes are expanded into adhesive pads. It has a pair of elongated black spots on the nape, and the top of the broad tail has a series of irregular black-edged yellowish bands. The colour of the body ranges from light to dark greyish brown with black flecks and whitish blotches. Interestingly, this is an all-female, oviparous species that reproduces by parthenogenesis, in which the embryos develop and grow without the need for fertilisation (hence it is a form of asexual reproduction). It is mostly nocturnal, and feeds on small arthropods as well as nectar and plant juice.
The Four-clawed Gecko (Gehyra mutilata) is commonly seen in human habitations and also wooded areas. It can grow to about 12cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes are expanded into adhesive pads. The colour of the body is pinkish brown with gold and blackish flecks. The tail is smooth. This lizard is nocturnal and feeds on insects.
The Lowland Dwarf Gecko (Hemiphyllodactylus typus) is usually found in mangroves, scrublands and forests. It can grow to about 10cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes are expanded into adhesive pads. The colour of the body is brown with dark markings. It has a prehensile tail (usually of a paler colour compared to the body) with a yellowish blotch at the base. It is nocturnal and feeds on insects.
The Kendall's Rock Gecko (Cnemaspis kendallii) is a forest species, and in Singapore is usually found in mature forests. It can grow to 14cm long, and like the previous geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The digits, however, are not expanded. It has a long snout that is slightly upturned. The pupils are distinctly rounded. The back of the body is yellowish with dark brown and white blotches. This oviparous gecko can be active both at night and in the day, feeding on insects on rock walls and trees.
The Peter's Bent-toed Gecko (Cyrtodactylus consobrinus) is usually found in mature forests. It is typically black or dark brown with whitish bands and net-like patterns. This rather large gecko can grow to about 28cm long. It is nocturnal, emerging to hunt small invertebrates at night.
Family Scincidae
Scincid lizards, commonly called skinks, generally have a smooth and slender body, short legs, and a long tail. They are usually covered in shiny scales, and the ones on the forehead are enlarged and usually symmetrically arranged. Some species live on the ground, while others may live on trees. Some ground species can also burrow, and these skinks tend to have short legs, or only two legs, or even no legs at all. A few species are semi-aquatic. Like the geckos, they can readily break off their tails to confuse predators, and grow new ones to replace the lost tails.
The Garden Supple Skink (Lygosoma bowringii) occurs in a variety of habitats, and can be seen in urban areas (in parks and among grasses), agricultural areas, and forests. It can grow to about 11cm long. The body is very slender and covered in shiny smooth or weakly keeled overlapping scales, bronze-brown in colour on the back and blackish with white spots on the sides. There is an orange patch behind each eye, and the large scales on the top of the head are symmetrically arranged. The limbs are orange in colour and are very small. This oviparous skink is a diurnal animal, and hunts for small invertebrates among the leaf litter and undergrowth, or in the soil.
The Many-lined Sun Skink (Eutropis multifasciata) has a robust body covered in shiny overlapping and strongly keeled scales. The large scales on the forehead are symmetrically arranged. The back is bronze-brown, and some may have a series of black lines. The sides of the body are either blackish or brown with white spots, or orange from the ear to the hind leg.
The above photo features one which has an orange band on each side of the body. Many-lined Sun Skinks can grow to about 35cm long. They are mostly terrestrial, and can be seen basking on the ground on sunny days. This ovoviviparous species can be found in a variety of habitats, such as inland forests, coastal forests, agricultural areas, parks and gardens. They feed on small invertebrates.
The Mangrove Skink (Emoia atrocostata) is rarely seen in Singapore. It occurs in mangrove forests and sometimes rocky shores. It can grow to about 26cm long, and is covered in smooth overlapping scales. The body is greyish brown with whitish spots above, and somewhat bluish with a blackish strip and whitish spots along the sides. The large scales on the forehead are symmetrically arranged. It is diurnal, and is usually found on the forest floor, on the roots or sometimes on tree trunks. This species is oviparous, and feeds on insects and small crustaceans.
References
Lizards and snakes are of the same order, Squamata. They can be distinguished from other reptiles by their relatively slender bodies that are covered by scales; extremely movable upper jaws which allows them to swallow relatively large prey; and the males possessing penises that that in pairs (each called a hemipenis).
Like most other reptiles, they have limited physiological means to maintain the body temperature within a narrow range, and are more reliant on external heat sources. Like other vertebrates, they have a backbone with a spinal cord (a hollow tube of nervous tissue).
Depending on the species, lizards may lay eggs (oviparous), bear live young (viviparous), or bear live young from eggs brood within the body (ovoviviparous).
Many people dislike or even fear lizards, but most lizards are quite harmless and even help to control the population of insect pests in homes and gardens. Most lizards are also not venomous.
I have only seen some of the lizards that can be found in Singapore, and have photographed even fewer of them. I certainly hope to eventually see more species during my future trips so that I can update this blog post. Here are just some of those that I managed to photograph:
Family Varanidae
Varanid lizards, commonly called monitor lizards, are usually large lizards with sharp claws, a relatively long neck, a powerful tail, and a forked tongue, much like those of snakes. The tongue is extended every now and then to "taste" the air for the scent of food. Monitor lizards are mostly carnivorous, though a few species are known to be frugivorous (i.e. eat fruits). Studies have shown that some species of monitor lizards are venomous, and are closely related to snakes. They lay eggs with soft shells.
The Malayan Water Monitor (Varanus salvator) is one of the largest lizards in the world, being able to grow to about 3m long, though most are below 2m. It has thick and leathery skin with non-overlapping scales. Like other monitor lizards, it has a forked tongue.
The nostrils are positioned close to the tip of the snout. Young Malayan Water Monitors are black with yellow spots, while the adults are usually plain greyish brown. They can swim and climb very well, and are commonly seen in coastal areas such as mangroves, islands, and coral reefs. They are also often seen in agricultural areas, parks, canals, and reservoirs. During the breeding seasons, males can be seen fighting by standing on the hind legs and hugging each other, supported by the powerful tail, clawing at each other's back. Malayan Water Monitors feed on carrion or hunt for fishes and other small animals. They are often trapped by locals for their meat, which is consumed, and their hides, which can be made into leather products.
The Clouded Monitor (Varanus nebulosus) is smaller than the previous species, growing to about 1.7m long. Like other monitor lizards, it has and forked tongue, thick and leathery skin, and non-overlapping scales. Unlike the previous species, the snout is relatively short with the nostrils positioned midway between the eye and the tip of the snout. The skin is greyish brown in colour, densely marked with yellow spots. Clouded Monitors hunt for small animals by digging among the leaf litter with their sharp claws. They are usually found in the forests and scrubland.
Family Agamidae
Agamids generally have long legs and tails, but short heads. They have rough scales covering their bodies, and many species have a crest running down the head to the back of the body. They are usually diurnal and live in trees and bushes, descending to the ground only to move to another tree or to lay eggs. In many cases, the females bury their eggs in the soil. Most species feed on small animals, but some larger species feed on flowers, seeds and other plant parts as well.
The Changeable Lizard (Calotes versicolor) is an introduced species that is commonly seen in urban parks, scrubland and forest edges. It can change its colour, but not as dramatically or quickly as the chameleon. It is native to Peninsular Malaysia, Thailand and other parts of mainland Southeast Asia. Growing to about 38cm, this lizard has strongly keeled scales, a relatively large head, long slender limbs, a long tail and a spiny crest running down the back of its head to the back of the body.
This species is rather variable and changeable in colour, and can be yellow, green or brown (sometimes with darker patterns). Juveniles and females may have a pair of pale stripes along their backs.
It can be differentiated from similar species by the two spines above the ear opening. Male Changeable Lizards are bigger with swollen cheeks, and the heads turn orange during the breeding season. They can be seen nodding their heads and doing push-ups during this period to court the females and to deter rival males. Like other agamids, Changeable Lizards are oviparous.
The Green Crested Lizard (Bronchocela cristatella) is native to Singapore. While it is largely displaced by the previous species in urban areas and forest edges, it is still fairly common in parks that have many shrubs and trees, and in the forest. Growing to about 58cm long, it has a moderately slender body with small strongly keeled scales, long slender limbs, a very long tail, and a spiny crest at the back of its head.
Green Crested Lizards are usually bluish green in colour, but may change to dark brown, such as the male in the above picture, which changed from green to brown during courtship, but changed back to bright green after mating. They are diurnal, and are usually found on trees or bushes. The females bury their eggs in the soil.
The Common Flying Dragon (Draco sumatranus) is a gliding lizard which can glide from tree to tree. Growing to about 22cm long, it has a slender body with small scales, long slender limbs and a very long tail. The body is light brown, marked with darker and lighter blotches. There is a broad flap of skin (patagium) supported by ribs on both sides of its body which is black in colour with irregular brownish and greenish patterns. It glides by launching off into the air and extending its patagium, much like a gliding kite. The male has a bluish head and a large yellow throat flap, as featured in the picture above. The throat flap is usually extended for courtship purposes or to deter other males.
The female Common Flying Dragon lacks the bluish head, and has a much smaller throat flap. This oviparous species can be found in the forest, agricultural areas and parks.
The Black-bearded Flying Dragon (Draco melanopogon) grows to about 24cm long. Like the previous species, it has a slender body with small scales, long slender limbs and a very long tail. The back of the body is olive or green with greyish brown bars or blotches, while the patagium is black with many yellow spots. The throat flap of the males is black and orange, and hence the common name Black-bearded Flying Dragon. Like other gliding lizards, it can glide from tree to tree by extending the patagium at the sides of the body, and display the throat flap during territorial dispute or courtship. This oviparous species is usually found in mature forests.
The Five-banded Flying Dragon (Draco quinquefasciatus) grows to about 27cm, and is usually found in mature forests, often near water bodies. While it is also greenish in colour, it can be differentiated from the previous species by the five dark bands marked with numerous white spots across its back, and the pinkish-orange patagium. The throat flap of the male is yellow in colour, while those of the female is greenish with yellowish spots.
Family Gekkonidae
Gekkonid lizards, commonly called geckos, have thin and delicate skin with tiny scales and large eyes without movable eyelids. Most species are nocturnal, but some are diurnal or both. If they are caught by the tail, they are able to break it to escape while the broken tail continues to wriggle about to confuse the predator. A new tail will eventually grow to replace the lost one. Some geckos have expanded fingers and toes functioning like adhesive pads. The underside of these pads is lined a series of skin flaps with numerous microscopic hook-like hairs which allow the gecko to walk on vertical surfaces and even upside-down. Geckos are oviparous.
The Spiny-tailed House Gecko (Hemidactylus frenatus) is a very common gecko in human habitations, and sometimes in the forest. It can grow to about 13cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes and fingers are expanded into adhesive pads. The colour of this lizard is rather variable, but is generally a pale greenish brown with irregular darker speckles. The tail has numerous spiky structures (tubercles). This oviparous gecko can be active both in the night and in the day, hunting for insects.
The Mourning Gecko (Lepidodactylus lugubris), also known as the Maritime Gecko, is quite widespread in Singapore though more commonly seen in coastal habitats. It can be seen in scrublands, coastal forests, mangrove forests, and sometimes in buildings. It can grow to about 10cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes are expanded into adhesive pads. It has a pair of elongated black spots on the nape, and the top of the broad tail has a series of irregular black-edged yellowish bands. The colour of the body ranges from light to dark greyish brown with black flecks and whitish blotches. Interestingly, this is an all-female, oviparous species that reproduces by parthenogenesis, in which the embryos develop and grow without the need for fertilisation (hence it is a form of asexual reproduction). It is mostly nocturnal, and feeds on small arthropods as well as nectar and plant juice.
The Four-clawed Gecko (Gehyra mutilata) is commonly seen in human habitations and also wooded areas. It can grow to about 12cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes are expanded into adhesive pads. The colour of the body is pinkish brown with gold and blackish flecks. The tail is smooth. This lizard is nocturnal and feeds on insects.
The Lowland Dwarf Gecko (Hemiphyllodactylus typus) is usually found in mangroves, scrublands and forests. It can grow to about 10cm long, and like other geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The toes are expanded into adhesive pads. The colour of the body is brown with dark markings. It has a prehensile tail (usually of a paler colour compared to the body) with a yellowish blotch at the base. It is nocturnal and feeds on insects.
The Kendall's Rock Gecko (Cnemaspis kendallii) is a forest species, and in Singapore is usually found in mature forests. It can grow to 14cm long, and like the previous geckos, has thin skin with tiny non-overlapping scales and large eyes without movable eyelids. The digits, however, are not expanded. It has a long snout that is slightly upturned. The pupils are distinctly rounded. The back of the body is yellowish with dark brown and white blotches. This oviparous gecko can be active both at night and in the day, feeding on insects on rock walls and trees.
The Peter's Bent-toed Gecko (Cyrtodactylus consobrinus) is usually found in mature forests. It is typically black or dark brown with whitish bands and net-like patterns. This rather large gecko can grow to about 28cm long. It is nocturnal, emerging to hunt small invertebrates at night.
Family Scincidae
Scincid lizards, commonly called skinks, generally have a smooth and slender body, short legs, and a long tail. They are usually covered in shiny scales, and the ones on the forehead are enlarged and usually symmetrically arranged. Some species live on the ground, while others may live on trees. Some ground species can also burrow, and these skinks tend to have short legs, or only two legs, or even no legs at all. A few species are semi-aquatic. Like the geckos, they can readily break off their tails to confuse predators, and grow new ones to replace the lost tails.
The Garden Supple Skink (Lygosoma bowringii) occurs in a variety of habitats, and can be seen in urban areas (in parks and among grasses), agricultural areas, and forests. It can grow to about 11cm long. The body is very slender and covered in shiny smooth or weakly keeled overlapping scales, bronze-brown in colour on the back and blackish with white spots on the sides. There is an orange patch behind each eye, and the large scales on the top of the head are symmetrically arranged. The limbs are orange in colour and are very small. This oviparous skink is a diurnal animal, and hunts for small invertebrates among the leaf litter and undergrowth, or in the soil.
The Many-lined Sun Skink (Eutropis multifasciata) has a robust body covered in shiny overlapping and strongly keeled scales. The large scales on the forehead are symmetrically arranged. The back is bronze-brown, and some may have a series of black lines. The sides of the body are either blackish or brown with white spots, or orange from the ear to the hind leg.
The above photo features one which has an orange band on each side of the body. Many-lined Sun Skinks can grow to about 35cm long. They are mostly terrestrial, and can be seen basking on the ground on sunny days. This ovoviviparous species can be found in a variety of habitats, such as inland forests, coastal forests, agricultural areas, parks and gardens. They feed on small invertebrates.
The Mangrove Skink (Emoia atrocostata) is rarely seen in Singapore. It occurs in mangrove forests and sometimes rocky shores. It can grow to about 26cm long, and is covered in smooth overlapping scales. The body is greyish brown with whitish spots above, and somewhat bluish with a blackish strip and whitish spots along the sides. The large scales on the forehead are symmetrically arranged. It is diurnal, and is usually found on the forest floor, on the roots or sometimes on tree trunks. This species is oviparous, and feeds on insects and small crustaceans.
References
- Baker, N. 2013. Ecology Asia. Retrieved Feb 12, 2013, from http://www.ecologyasia.com.
- Baker, N. & K. Lim, (Vertebrate Study Group, Nature Society Singapore). 2008. Wild Animals Of Singapore. Draco Publishing and Distribution Pte. Ltd. 180 pp.
- Das, I. 2010. A Field Guide to the Reptiles of South-east Asia. New Holland Publishers (UK) Ltd. 376 pp.
- Lim, K.P. & L. K. Lim. 1992. A Guide to the Amphibians & Reptiles of Singapore. Singapore Science Centre. 160 pp.
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